I have an image which I can freely move, rotate and resize behind a fixed frame (fixed position and size). How can I find out with JavaScript/jQuery if the background from the bounding-box of the rotated image is inside the frame?

Interesting question! But: you actually want to check if the cropping area is within the bounding-box of the background. For me this is a huge difference. Feel free to edit your question. Tip: you can also inline images in your question (I'd suggest you to make it a bit smaller 300px - 500px width).
–
try-catch-finallyJan 20 '13 at 16:53

Have you tried searching? The getBoundingClientRect() was new to me. The first test worked fine with latest Firefox, but maybe there are issues with other browsers. If this is not sufficient, math, to be more precisely trigonometics is what you need.
–
try-catch-finallyJan 20 '13 at 17:28

Cant you just test if every corner of the frame is in the background? With trigonometric indeed.
–
RickyAJan 21 '13 at 19:05